Slip Resistant Composite Decking: Which Rating Your Project Needs, and What We Can Evidence
There is no single slip rating. There are three separate test systems, they measure different things under different contaminants, and — this is the part that costs people money — a result from one cannot be converted into a result from another.
This page explains which system applies to your project, what our own test actually says, and which classifications we do not hold. If you only take one thing away: find out which method your authority accepts before you start comparing products.
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R10
AS 4586 App. D · Intertek report
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15°
Mid-band in the 10–19° R10 range
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Shod, oil-wet
The condition actually tested
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One profile
ZSGJ138H23A only
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No DIN 51097
Barefoot wet not tested
Three Test Systems, Three Different Questions
Slip resistance is not one number. Which system applies depends on what is on the floor and what is on the foot, and the three do not answer each other's question.
How each test is actually run
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DIN 51130 — shod ramp
An operator in standard footwear walks up and down a ramp coated in lubricating oil. The angle at which walking fails gives a rating from R9 to R13. AS 4586 Appendix D is the harmonised version and uses the same R scale.
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DIN 51097 — barefoot ramp
The same ramp, but barefoot and with water rather than oil. Results are Class A, B or C. This is the test written into specifications for pools, spas and changing areas.
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BS 7976 — pendulum
A weighted arm with a rubber slider swings across the surface, and the friction is read off as a Pendulum Test Value. This is the method the HSE prefers in the UK and the one most UK specifiers ask for.
What the R Numbers Actually Mean
The R scale is simply the ramp angle at which walking fails, banded. Nothing more sophisticated than that.
| Classification | Ramp angle | Note |
|---|---|---|
| R9 | 6–10° | |
| R10 | 10–19° | Our tested result, 15°, sits in the middle of this band |
| R11 | 19–27° | |
| R12 | 27–35° | |
| R13 | 35° and above |
Find Out Which Test Your Project Needs
Choose where the project is, how the surface is walked on and what condition matters. This tells you which method is normally specified, what it reports, and whether we currently hold it — including when the answer is no.
The One Thing That Costs People Money
These three results do not convert into one another. Not approximately, not with a correction factor, not at all.
The reason is physical rather than bureaucratic. The shod ramp uses a cleated boot on oil. The barefoot ramp uses skin on water. The pendulum uses a rubber slider. Different contact material, different contaminant, different mechanism — so there is no established correlation between them, and none of the bodies that publish these standards offers a conversion.
What goes wrong in practice
A buyer collects quotations from four suppliers. One quotes R11, one quotes Class C, one quotes a PTV of 40, one quotes nothing. They look comparable on a spreadsheet and they are not comparable at all — three of those numbers answer three different questions, and at least two of them are probably answering a question this project never asked.
What to do instead
Ask the authority, the specifier or the building control body which method they will accept, and get that answer before you shortlist products. Then ask every supplier for that specific test. A supplier who responds with a different test and calls it equivalent is either confused or hoping you are.
Which Profile the Test Was Actually Done On
A slip result belongs to the profile that was tested, not to a product range. This is where ours applies and where it does not.
Co-extrusion Decking Board
23 × 138 mm · ZSGJ138H23A
The profile the R10 result was obtained on. This is the only product our slip report covers.
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Co-extrusion Wide Board
23 × 148 mm
Same co-extruded range and surface family, but a different profile. Not covered by the report, and we will not present it as if it were.
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Composite Stair Tread
138 × 22.5 mm
A separate moulded section. Not slip tested. Stairs are exactly where a figure matters most, so ask early if your project needs one.
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Co-extrusion Deck Tile
Direct-lay, capped
Not slip tested. Tiles are often specified for terraces and pool surrounds, which is usually a barefoot wet question — see below.
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Already know which test you need?
Tell us the method, the classification and the country, and we will tell you straight away whether we hold it, and what testing would cost and take if we do not.
What We Hold and What We Do Not
Stated precisely, because a slip figure quoted loosely is worse than no figure at all.
What we hold
An R10 classification. Intertek report 230625005SHF-001, tested to AS 4586-2013 Appendix D — the oil-wet inclining platform, walked in shoes — with a measured angle of 15°, which sits in the middle of the 10–19° R10 band rather than at its edge. Because AS 4586 Appendix D and DIN 51130 are harmonised on the same R scale, a European specifier reads this on the scale they already use.
What that result covers
One profile: ZSGJ138H23A, the 23 × 138 mm co-extruded decking board. It does not cover the wide board, the stair tread, the deck tiles, the classic uncapped range or any fencing product. Surface texture, cap formulation and profile geometry all affect the result, so a test on one section is not evidence for another.
What we do not hold
DIN 51097 — the barefoot wet classification, A/B/C — has not been tested on any of our profiles. That is the test that pool, spa and changing-area specifications are written around, so for those projects we currently have nothing to offer. We also hold no pendulum PTV for UK specifications, and no US slip data and no ICC-ES evaluation report.
If your project needs something we do not have
Say so at design stage rather than at approval stage. Testing can be arranged on the specific profile you intend to use: the testing cost is paid up front and credited in full against your order. That is slower than a confident answer, but a confident answer that fails an inspection is considerably slower.
Common Scenarios and What They Usually Ask For
Indicative only — the authority for your project has the final say on which method it accepts.
| Scenario | Usually assessed by | Do we hold it? |
|---|---|---|
| Garden or terrace deck, shoes, continental EU | DIN 51130 — R rating | Yes — R10, profile ZSGJ138H23A only |
| Garden or terrace deck, shoes, UK | BS 7976 pendulum — PTV | No |
| Pool surround or spa, barefoot | DIN 51097 — Class A / B / C | No |
| Outdoor stairs, shoes | R rating, on the tread profile | Not on the tread profile |
| Commercial or public walkway, EU | R rating, often with a fire classification as well | R10 on one profile; no EN 13501-1 |
| Any US project | DCOF or ASTM-based practice | No |
Slip Resistance: Common Questions
Understanding the ratings
Is R10 good?
It is a statement of fact rather than a grade. R10 means the tested surface stayed walkable on an oil-coated ramp between 10° and 19°, in shoes. Whether that is sufficient depends entirely on the project, and on whether an R rating is the right question in the first place. For a barefoot wet area it is not the right question at all.
Can you convert R10 into a PTV or into a Class B?
No, and nobody can. The three tests use different contact materials and different contaminants, there is no established correlation between them, and no standards body publishes a conversion. Any supplier offering one is guessing.
What is the difference between DIN 51130 and AS 4586 Appendix D?
They are the same oil-wet shod ramp method on the same R9 to R13 scale; the Australian standard was harmonised with the German one. Our report is to AS 4586 Appendix D, which is why the result is expressed as an R rating that a European reader recognises.
Why does barefoot need a different test?
Skin on water behaves nothing like a cleated boot on oil. DIN 51097 therefore uses a barefoot operator with water and reports Class A, B or C. It exists precisely because the shod result cannot answer the barefoot question.
What applies to our products
Does the R10 apply to all your decking?
No. It applies to profile ZSGJ138H23A, the 23 × 138 mm co-extruded board, and to nothing else. Profile geometry, surface texture and cap formulation all affect the result, so we do not extend it to the wide board, the stair treads, the tiles, the classic range or any fencing product.
Do you have a slip figure for the stair treads?
Not at present. The stair tread is a separate 138 × 22.5 mm moulded profile and has not been tested. Stairs are where slip performance matters most, so if your project needs a classification on the tread, raise it early and we will arrange testing.
We are specifying a pool surround. What can you offer?
For the barefoot wet classification, nothing today — we do not hold DIN 51097 on any profile. We would rather tell you that now than have it surface at approval. If the project can carry the programme, testing on the specific profile can be arranged.
Getting what your project needs
How do we get a classification you do not currently hold?
Tell us the standard, the classification level and the profile. Testing is arranged with an accredited laboratory; the cost is paid up front and credited in full against your order. We will give you the cost and the lead time before you commit to anything.
What should we ask other suppliers?
Ask for the standard, the report number, the laboratory, the exact profile tested and the date. A classification quoted without those five things cannot be checked, and a figure that cannot be checked is not evidence. Apply the same test to us.
Can we see and test the board ourselves?
Samples are free — you cover the courier, and we credit it against your first order. Several buyers send samples to their own laboratory, which is a perfectly reasonable thing to do.
Tell us which slip standard your project is written around
The standard, the classification level, the profile you are considering and the country. We will confirm whether we hold it, and if not, what testing costs and how long it takes.
Find out which test applies before you compare products
Send the standard your project is written around and we will tell you plainly whether we can evidence it. Where we cannot, we will say so and quote the testing instead.